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  • Users: asco1
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  1. asco1

    Self Tapping Screws

    Use Thread Forming Screws...no chips...better grip.
  2. asco1

    The hole of cable lug?

    If there is any movement of the cable, a 1-hole lug may become loose (and then hot) or short to another phase or ground. Movement can be caused by tension of heavy cable & vibration, magnitizim during a short circuit, or just someone pulling on the cable. NEMA has developed a standard. (2) 1/2"...
  3. asco1

    Short-Circuit protection of a three phase motor with two fuses?

    If there is a short on B-Phase, any available current will pass through the B-Phase of your contactor. If the avaible current is above 4500A, the contactor will fail.
  4. asco1

    Short-Circuit protection of a three phase motor with two fuses?

    Overcurrent Protection is to protect the Conductors & the Devices they feed during normal operation. In this case, this is the job of your circuit breaker. Your Conductors & your Overcurrent Protection Device (your breaker) have specific short circuit ratings. The short circuit rating is the...
  5. asco1

    Switchboard

    To a UL 891 Switchboard manufacturer, 100% can mean a few different things. 1. Sized and spaced per the manufacturers temperature test results: Most of the current flows along the skin of a bus bar. Therefore you might get a greater current carrying capacity with a lower density, large surface...
  6. asco1

    Switchboard

    To a UL 891 Switchboard manufacturer, 100% can mean a few different things. 1. Sized and spaced per the manufacturers temperature test results: Most of the current flows along the skin of a bus bar. Therefore you might get a greater current carrying capacity with a lower density, large surface...
  7. asco1

    Bus Bracing for Low Voltage Switchgear

    Re UL 891: There is no more Suppliment B. See Annex G (at the very end of the 891 file). Annex G covers 4000A maximum & up to 100,000 RMS. 1558 Switchgear: Supports & bracing must be per individual testing. Once that testing has been done, we can design per the spacings in our UL File.
  8. asco1

    Metal Clad Switchgear Thicker gauge other than 11 gauge

    Typical switchgear is a bolted frame construction. For the most part, a heaver gauge material will not prevent twisting. Gear must be level and square for drawout breakers to opperate properly. Proper installation is everything. An option is to order switchgear with a seismic rating...
  9. asco1

    How to calculate Ampacity of a Rectangular Copper Bar

    Waross, you are correct in you assessment....The 8" dimension is not to be taken into consideration. At 800A per sq in, you will need 20" of .25 cu to carry the 4000A. (the 8" dimension can be anything)
  10. asco1

    How to calculate Ampacity of a Rectangular Copper Bar

    Per UL891 Table 23 & 24: less than 3000A: 1000A per sq. in. 3000A - 6000A: 800A per sq. in This is what we typicaly use in our switchboards. Some city codes require 800A per sq. in. everywhere. Your .25 x 8.0 bar will need to be 20" (or double up so that you have 20" or more of .25 cu)
  11. asco1

    Circuit Breakers

    From a Switchboard/gear perspective: If the Breaker has a Non Interchangeable Trip....We size our cable/bus to the trip (AT). If the Breaker has an Interchangeable Trip, we size our cable/bus to the frame (AF). Also for a Fuse Holder or a Fused Switch, we'll size to the frame (or the maximum...
  12. asco1

    IP4LX What is the LX?

    I thought the same thing at first....mixing IEC & UL. But my search came up with this chinese site that plainly refers to IP4LX. It makes mention to IEC 529 but clearly does not mimic it. I've attached the chinese site...
  13. asco1

    IP4LX What is the LX?

    I have a customer inquiry from Argentina who is asking for a IP4LX enclosure. My googles have come up with only chinese web sites. I've translated the page, but I am still not clear. Can someone please define IP4LX for me. Thanks!
  14. asco1

    1 run in a two hole lug

    This is a common situation on breaker & switches. Torque & loctite or completly remove the unused set screw.
  15. asco1

    Type 4 Freestanding Enclosure, How do I Mount it?

    All Enclosure manufactures sell Type 4 & 12 Freestanding enclosures. But they have no means of securing the enclosure to the floor. No instructions. No kit. UL50 says "Floor supported enclosures are not required to be provided with a mounting means." I called Hoffman. They had no instruction...
  16. asco1

    Bus bar bracing

    See UL 891 Supplement B. It has a chart for between 42K & 100K, Max 4000A. Example:800A-4000A, 65,000 @ 480V, bars edge-edge, min. 1" bar to bar, min. 5" center to center, 21" between supports. Example:800A-4000A, 65,000 @ 480V, bars face-face, min. 4" bar to bar, min. 6" center to center...
  17. asco1

    Switchgear versus switchboards

    UL891 (Switchboards) contains defined minimum bus ampacities, bus spacing, & bus arrangements. 891 also defines minimum support & bracing requirements based upon the necessary short circuit requirements. Basically, UL891 is an engineering guideline for building safe equipment that will meet NEC...
  18. asco1

    Switchgear versus switchboards

    Switchboards are built to engineering guidlines set out in UL 891. Switchgear is built to UL 1558.
  19. asco1

    Slots/holes on bus bars, what's the effect?

    UL 891 says "Part of the bus material may be removed for slots or holes (wether used or not) if the remaining material at any cross section along the bus bar has at least 70 percent of the required ampacity and the remaining metal in any 6 inch length of bus is at least 93 percent of the metal...
  20. asco1

    Joining Line Segments

    We are using 2002. Is there a way to join two line segments? Thanks!

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